Power converters are commonly used to convert AC power from a generator to DC power, and then from DC power to AC power for use by a motor. Power conversion may require high-speed switching of large currents by power semiconductor devices, such as insulated gate bipolar transistors (IGBTs). An electric drive traction application typically includes both AC/DC conversion to receive power from a generator and DC/AC conversion to power a motor. The generator is typically driven by an engine.
Different power converter applications may also have different requirements for locations of external connections. Such connections may include DC connections, AC connections, coolant connections, control connections, and accessory connections. Power converters may be used in different locations on a machine, and each location may require different locations for the connections. For example, a power converter may be connected to a generator or a motor, each of which is located on a different part of the machine. Likewise, if the machine has two or more drive motors, a power converter may require different locations for the connections. For example, motors on the front and rear or left and right sides of the machine may require connection locations that are mirror images of the other. This would normally require a new power converter to be developed for each location.
The cost of designing a power converter is considerable. Significant engineering time is required for proper bus bar routing, board layouts, housing design, and power module design. The design cost for power modules is particularly high. Tooling is also an important consideration. For example, the tooling for a single housing design can be in excess of $100,000. Each time a new power converter is designed for a new application, new tooling is needed. Typically, a single housing design cannot be used for different power converter designs.
Accordingly, the power converter is a significant portion of an electric drivetrain cost. Production volumes are needed to drive down costs in order to make electric drivetrains feasible for more applications in a product line. Therefore it is desirable to design a power converter package that can be adapted to a large number of configurations while changing a minimum number of components. Thus, the power converter design can fulfill the needs of an entire product line of electric drivetrains thereby saving NRE and tooling costs associated with creating new designs for every application.
United States Patent Application No. 20060120001 to Weber et al., issued Jun. 8, 2006, entitled “Modular power supply assembly,” known hereafter as the Weber Reference. The Weber Reference discloses “A modular power converter that is easily adapted to a wide variety of applications . . . . ” However, The Weber Reference takes a very different approach from the current disclosure and states that “A fundamental approach of the present design is to separate the typical drive inverter and converter design functions of a power converter into separate assemblies.” Different parts of the chassis or housing are changed out in order to adapt to different applications. The number of different parts requires a large number of designs in order to meet the needs of those applications. In addition, the heat sink design disclosed by Weber et al. does not account for coolant connections from different sides of the power converter.